Experimental Study of the Interactions Between Air Flow Rate Modulations and PVC in a Swirl-Stabilised Liquid Fuel Burner

Abstract

In a swirl-stabilised liquid fuel burner, the fuel spray response to the Precessing Vortex Core (PVC) and air flow rate modulations is analysed in non-reacting conditions. A siren-like device is used to modulate the air flow rate at a frequency corresponding to longitudinal combustion instability oscillations observed during reacting tests. Time-resolved Mie scattering images of the fuel spray are recorded and treated with multiple post-processing methods based on Dynamic Mode Decomposition. The spray velocity fluctuations induced by the PVC and the siren-generated modulations are extracted from noisy datasets and studied. The evolution of the PVC impact on the spray for different levels of flow rate fluctuations is followed and a nonlinear interaction mode is highlighted for several intensities of flow rate modulations. It is shown that increasing the flow rate modulations tend to weaken the PVC impact on the spray, progressively disturbing its structure, starting from the downstream part and progressing upstream. These observations on the fuel spray can be used to understand and interpret data obtained in reacting conditions, for example when competition between PVC and longitudinal combustion instabilities occurs.

Experimental Study of Thermo-Acoustic Instability Triggering in a Staged Liquid Fuel Combustor Using High-Speed OH-PLIF

“…What is first striking is the disappearance of the peak around 184 Hz which was attributed to rotational motions of the flame. Previous studies have observed the disappearance of convective rotational structures when the combustor is submitted to high-amplitude pressure oscillations [22][23][24]. A similar phenomenon might be at stake here.…”

Identification and dynamics of coherent structures in a Coanda swirling jet flow

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Comprehensive Combustion Stability Analysis Using Dynamic Mode Decomposition

“…The latter is made possible by mapping temporal domain to spatial domain , for analyzing spatially evolving dynamics. DMD in combustion science is a burgeoning area, and its applications are quickly growing. − However, further investigations are required to fully understand the significance of coherent structures and their Ritz values, growth factors, and energy contents driving combustion dynamics on flame stability. This study presents comprehensive analysis of DMD results on combustion stability.…”